Keep in mind that at standing height, the desk does have a little bit of wobble, especially if you use the castor wheels. My monitor was unsafely wobbly and I had to use a wood clamp to clamp it to the desk for safety. Part of this is due to my monitor- for a 28" screen, the included stand has a small (too small) footprint and odd weight distribution. For most monitors this probably won't be a problem.
I tend to stand until after lunchtime, then sit the rest of the day, depending on how heavy a lunch I eat. My back problems from a car accident 2 years ago have nearly disappeared. Best feature of a standing desk is eating lunch- your lap isn't in the path of falling food objects. If there is a spill imminent, you can simply dodge out of the way. I haven't spilled lunch on my pants since I got the desk.